PRO FOOTBALL; Bears Lose Miller To Steroid Suspension

Quarterback Jim Miller, who leaped unexpectedly from third string to starter this season for the Chicago Bears, was suspended today by the National Football League for four games for taking a dietary supplement containing an anabolic steroid.

The suspension was the first for an N.F.L. quarterback for using steroids. It came at a particularly inopportune time for Miller, who had just begun to make his mark in the league, and for the 5-7 Bears, who are a playoff contender for the first time since 1994.

Miller had been a pleasant surprise to the Bears this season, contributing significantly to recent victories over San Diego and Green Bay. He became the third N.F.L. player to be suspended in the past two weeks for using steroids; Lyle West, a rookie Giants safety, and Jason Ferguson, a Jets tackle, also received four-week suspensions. Several Jets teammates said Ferguson had been taking an over-the-counter weight-reducing product that contained a banned substance.

Miller, at a news conference today at the Bears' headquarters in Lake Forest, Ill., said he had taken the banned substance nandrolone unintentionally. He said he had not realized that nandrolone was contained in a dietary supplement he took to aid in his workouts.

''This is the truth; in no way was it done knowingly,'' the 28-year-old Miller said. ''I have taken a dietary supplement that any of you or any of the general public can purchase over the counter. I made a mistake in that I didn't read the bottle.''

Greg Aiello, an N.F.L. spokesman, said Miller had tested positive for the steroid in a random drug test in October. The league tests seven players from each team every week.

''Players are informed they're responsible for what's in their bodies,'' said Aiello, who would not comment on Miller's case but confirmed that he was the first quarterback to be suspended under the steroid policy.

The Bears, who have been plagued by quarterback problems this season, said they would welcome Miller back next year. Indeed, when Miller took over as the starting quarterback last month, his performance was solid, if unexpected. In addition to his play in key victories over Green Bay and San Diego, Miller's 3 touchdown passes and 422 passing yards in a loss to Minnesota represented the best performance by a Bears quarterback in 30 years.

His recent success represented a decided upswing in a previously unremarkable career. After being drafted by the Pittsburgh Steelers out of Michigan State in 1994, Miller played in the World League, then for Atlanta and Jacksonville in the N.F.L. before being picked up on waivers by the Bears.

He got his break this season after injuries sidelined quarterbacks Cade McNown and Shane Matthews. The Bears said Matthews would probably start Sunday's game against Green Bay.